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2.3.1. Model of Culvert Section with Fully Developed Flow Using Cyclic Boundary Conditions In this study, a simulation model was developed using the commercial CFD software STAR-CCM+. A small section of the culvert barrel was modeled with cyclic boundaries at the inlet and outlet sections of the computational domain. A 36 inch diameter culvert with corrugation size 3 inches by 1 inch has been used for this study. The flow depth was 9 inches, a flow velocity was 0.71 feet/second, and zero bed elevation in the culvert (no gravel present). Figure 2.6: Reduced symmetric section of the barrel considered from a trough to trough The boundary conditions used for the computational model in Figure 2.6 are listed in Table 2.1 below. All the CFD runs have been carried out with the same set of boundary conditions. Table 2.1: Boundary conditions Boundary Name Type Face at minimum x value Inlet Cyclic boundary condition Face at maximum x value Outlet Cyclic boundary condition Water surface Top Symmetry plane Centerline Center Symmetry plane all other surfaces Barrel No-slip wall TRACC/TFHRC Y1Q3 Page 18
2.3.2. Mesh Refinement Study As detailed in the previous quarterly report, a CFD procedure is being developed to test the flow conditions that are defined in the tables of the work plan from TFHRC [6]. As a part of developing the procedure, mesh refinement studies are being conducted for each geometry configuration in the work plan. Sensitivity to mesh refinement will need to be checked for the larger culverts in the work plan when the geometry for those culverts are built. In the process of mesh refinement various base sizes have been chosen, along with the creation of a volumetric control (annulus ring) along the corrugated section. The refinement of the mesh is defined by specifying a reduction of mesh size for volume within an annulus intersecting the model as shown in Figure 2.7. The volumetric control body intersecting the corrugated section provides a means to refine the mesh in the corrugated region of interest. The refined mesh enables better resolution of the flow field with recirculation zones at the troughs between the corrugations. Meshing also includes a prism layer consisting of orthogonal prismatic cells running parallel to the wall boundaries, which constitutes a boundary mesh that is good for the application of wall functions to compute the shear stress at the wall boundaries. Figure 2.7: Refined mesh area with respect to the base created using a volumetric control A volumetric control (annulus ring) was created intersecting the corrugated section to specially refine the mesh around this region with respect to the base as shown in Figure 2.7. Figure 2.8 does not show a coarser version of mesh 1 and mesh 4 because they look similar to mesh scenes 2 and 5 with larger cells. Sensitivity of the solution was tested with 6 variations of the mesh, including two base sizes and 4 combinations of refinement in the region with the corrugations where recirculation zones develop. The refinement is defined by specifying a reduction of mesh size for volume within a volumetric control as shown in Figure 2.7. TRACC/TFHRC Y1Q3 Page 19
Page 1 and 2: ANL/ESD/11-39 Computational Mechani
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Page 7 and 8: 3.3.4. Simplifying Assumptions ....
Page 9 and 10: Figure 2.22: Velocity distribution
Page 11 and 12: List of Tables Table 2.1: Boundary
Page 13 and 14: experiments at TFHRC continued. A m
Page 15 and 16: 2. Computational Fluid Dynamics for
Page 17 and 18: ( ) ( ) (2.8) where A 0, A 1, and n
Page 19 and 20: efine the rate function to improve
Page 21: The objective of this work is to de
Page 25 and 26: Table 2.2: Details of the various m
Page 27 and 28: indicating the surface averaged vel
Page 29 and 30: Figure 2.13: Line probes created at
Page 31 and 32: In Figure 2.15 the velocity and the
Page 33 and 34: Mesh 1 Mesh 2 Mesh 3 Mesh 4 Mesh 5
Page 35 and 36: Figure 2.20: Dimensional details of
Page 37 and 38: Figure 2.22: Velocity distribution
Page 39 and 40: Figure 2.25: CFD velocity contour p
Page 41 and 42: Figure 2.27: CFD velocity contour p
Page 43 and 44: Conclusions for Comparison with Exp
Page 45 and 46: 3.1.1.1. Approach To date, an initi
Page 47 and 48: Figure 3.4: Sampling domain [3] A c
Page 49 and 50: present. In addition during the sum
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Page 67 and 68: Figure 3.17: FEM Model of a Ford F-
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while the passive system has fixed
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the controllable EMSA. Simulations
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Figure 3.32 Comparison of the initi
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